Anticoagulant activity in salivary glands of ixodid ticks

Anticoagulant activities were determined in salivary gland extracts (SGE) from five ixodid ticks (Ixodes ricinus and Haemaphysalis inermis females; both females and males of Amblyomma variegatum, Rhipicephalus appendiculatus and Dermacentor reticulatus) by using standard coagulation assays - thrombin time (TT); prothrombin time (PT) and activated partial thromboplastin time (APTT). SGE of all examined ticks, except H. inermis, prolonged the TT in a protein dose-dependent manner. The ticks were also found to possess antihaemostatic factors against both the extrinsic (PT) and intrinsic (APTT) coagulation systems. Increase in clotting time in both the PT and APPT assay was related to lick SGE protein doses (except for H. inermis in the PT assay), however the intrinsic pathway was more sensitive to the anticoagulants than the extrinsic pathway at low protein concentrations. Female A. variegatum and R. appendiculatus SGEs were more potent than in males, while in D. reticulatus the anticoagulant activity was similar in both sexes (TT, APTT) or higher in males (PT). The results suggest that A. variegatum females possess the most potent anticoagulants acting in very low doses against different factors of the coagulation cascade.